1. Field of the Invention
The present invention relates to an image stabilization apparatus, an image capture apparatus comprising an image stabilization apparatus, and control methods thereof and, more particularly, to an image stabilization apparatus having an image blur correcting function, an image capture apparatus comprising such an image stabilization apparatus, and control methods thereof.
2. Description of the Related Art
There has conventionally been known an image capture apparatus, including an image stabilization apparatus which detects a shake of the image capture apparatus and drives a movable member (shake compensation lens and its holding member) to correct image blur arising from the shake. Shake detection in the image stabilization apparatus often uses an angular velocity sensor. The angular velocity sensor vibrates a vibration member such as a piezoelectric element at a predetermined frequency, and outputs, as angular velocity information, a voltage corresponding to a Coriolis force generated from a rotational motion component. The image stabilization apparatus integrates the obtained angular velocity information to obtain the magnitude and direction of the shake, and outputs a correction position control signal to drive the movable member so as to cancel the image blur. When driving the movable member, the current position of the movable member is fed back as a movable member position signal to the image stabilization apparatus. The image stabilization apparatus performs feedback control to output a correction position control signal corresponding to the movable member position signal.
In some cases, the user intentionally moves the image capture apparatus. An example is panning shooting to shoot an image while moving (rotating) the image capture apparatus horizontally. If the image stabilization apparatus detects the panning operation as a shake and drives the movable member, the shake compensation lens has moved by a maximum amount (maximum driving position) by the end of the panning operation in a direction in which the shake generated by the panning operation is canceled. This is because a shake generated by the panning operation is generally too large to cancel even if the shake compensation lens is moved by a maximum amount. At the end of the panning operation, the shake compensation lens cannot be moved in this direction any more, and no satisfactory image blur correction can be performed. To solve this problem, there is known panning control to forcibly center the shake compensation lens position when the correction amount becomes large due to the panning operation.
When shooting a still image with an image capture apparatus including the image stabilization apparatus, the anti-shake capacity is desirably high. However, if panning control acts, though the user does not actually perform panning shooting, the anti-shake capacity becomes poor.
To achieve both panning control and the anti-shake capacity, it is proposed to shift quickly to panning control at a high shutter speed at which the influence of camera shake hardly appears, and shift less quickly to panning control at a low shutter speed at which the influence of camera shake readily appears (Japanese Patent Laid-Open No. 2006-201723).
However, the method disclosed in Japanese Patent Laid-Open No. 2006-201723 neither suppresses a phenomenon in which the shake compensation lens stays at the maximum driving position, nor suppresses degradation of the image quality caused by deviation of the shake compensation lens from the center of the optical axis of the imaging optical system while providing an anti-shake capacity necessary for the situation.